Surge bin

ABSTRACT

A surge bin having a top and a bottom comprising: a plurality of walls defining an inner chamber; and an opening at or near the top of the surge bin and a discharge outlet at or near the bottom of the surge bin, the discharge outlet positioned to discharge particulate material onto a conveyor; whereby at least one of the plurality of walls having a sloped portion sloping outwards towards the discharge outlet.

The present invention relates to surge bins for particulate material processing systems and more particularly to a surge bin that is modified for use with high grade oil sand.

BACKGROUND OF THE INVENTION

Surge bins are used to provide a relatively constant feed of particulate material in a particulate material processing system. Surge bins are typically an open topped container with a discharge outlet provided near the bottom of the surge bin. The surge bin collects the particulate material while discharging it out the bottom end so that an irregular supply of the particulate matter to the system can be accumulated and metered into a relatively constant flow of particulate material out of the surge bin.

Surge bins are sized based on expected surges of particulate material to the surge bin. The size of the surge bin is chosen so that when the flow rate of particulate material entering the surge bin is greater than the desired flow rate exiting the surge bin (i.e. a surge is occurring) the additional particulate material collects in the surge bin. When the flow rate of the particulate material entering the surge bin is less than the desired flow rate of particulate material exiting the bin, the extra particulate material that has collected in the surge bin during the previous surge can be used to keep the flow rate of particulate material that is being discharged from the surge bin relatively constant until the next surge of particulate material into the surge bin occurs.

Surge bins are typically used in oil sands mining operations because the inputs to the oil sand processing system are often irregular. In an oil sand mining operation, oil sand is typically mined at a mine face using a power shovel. This power shovel may then supply the mined oil sand to the oil sand processing system or it may load the mined oil sand into a large truck for transport to the oil sand processing system. This supply of oil sand to the oil sand processing system by either the power shovel or the transport trucks results in more oil sand being supplied to the oil sand processing system at certain times (i.e. a surge when a power shovel or a transport truck is supplying a load of oil sand to the oil sand processing system) and significantly less oil sand or even no oil sand being supplied at other times (i.e. when the power shovel is collecting oil sand ore from the mine face or between truck loads). To address this irregularity in the supply of mined oil sand to the system, surge bins are commonly used within the system to try and meter the flow of oil sand in the system so that a relatively constant feed rate of oil sand occurs in the system. In some oil sand processing systems, a surge bin is provided over top of a conveyor, such as an apron feeder. The flow rate of oil sand out of the surge bin can be somewhat controlled by varying the speed of operation of the conveyor.

Most surge bins are designed based on the principles of granular flow materials such as masonry sand. However, oil sand and particularly high grade oil sand does not typically act like conventional granular materials and does not flow like conventional granular materials which can cause flow problems when surge bins are used. For example, when conventional granular materials are used in a surge bin provided over top of a conveyor, the flow rates of the granular material out of the surge bin are proportional to the speed of operation of the conveyor. Increasing the speed of operation of the conveyor will typically increase the flow rate of the granular material from the surge bin. When lower to average quality oil sand are being used in these surge bins (i.e. oil sand with relatively low bitumen content, typically having less than 9 wt % bitumen, the flow rate of the oil sand from the surge bins is also typically proportional with the speed of the conveyor. However, when high grade oil sand is being used in these surge bins (i.e. oil sand with relatively high bitumen content and low fines content, typically having around 10-13 wt % bitumen, the flow rate from the surge bins can reach a limit where further increases in the speed of operation of the conveyor do not result in further increases to the flow rate of oil sand from the surge bin. This can result in throughput limitations in the oil sand processing system which can adversely affect the production from the system that would not be present if a more conventional granular material, such as masonry sand, was being used in the system.

Currently, a number of strategies are used to try and prevent this upper limit on the flow rate from occurring when high quality oil sand is used. One strategy to avoid this flow rate limitation is to add air to the surge bin. Another strategy is to maintain proper blending of high grade oil sand with lower to average grade oil sand to keep the overall grade of oil sand that enters the surge bin at an acceptable level. However, due to unexpected shovel outages or where oil sand deposits have significant quantities of high grade oil sand ore, blending high grade oil sand with lower grade oil sand to reduce the quality to an acceptable level is not always a viable and/or desirable option.

SUMMARY OF THE INVENTION

It is to be understood that other aspects of the present invention will become readily apparent to those skilled in the art from the following detailed description, wherein various embodiments of the invention are shown and described by way of illustration. As will be realized, the invention is capable for other and different embodiments and its several details are capable of modification in various other respects, all without departing from the spirit and scope of the present invention. Accordingly the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive.

In one aspect of the present invention, a surge bin having a top and a bottom is provided, comprising:

-   -   a plurality of walls defining an inner chamber; and     -   an opening at or near the top of the surge bin and a discharge         outlet at or near the bottom of the surge bin, the discharge         outlet positioned to discharge particulate material onto a         conveyor;     -   whereby at least one of the plurality of walls having a sloped         portion sloping outwards towards the discharge outlet.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the drawings wherein like reference numerals indicate similar parts throughout the several views, several aspects of the present invention are illustrated by way of example, and not by way of limitation, in detail in the figures, wherein:

FIG. 1 is a schematic illustration of an oil sand processing system where mined oil sand is processed to form it into a pumpable oil sand slurry;

FIG. 2 is schematic illustration of a prior art surge bin;

FIG. 3 is a schematic illustration of a surge bin in one aspect of the invention; and

FIG. 4 is a graph illustrating the different flow rates from a surge bin as shown in FIG. 2 and a surge bin as shown in FIG. 3.

DESCRIPTION OF VARIOUS EMBODIMENTS

The detailed description set forth below in connection with the appended drawings is intended as a description of various embodiments of the present invention and is not intended to represent the only embodiments contemplated by the inventor. The detailed description includes specific details for the purpose of providing a comprehensive understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without these specific details.

FIGS. 1A and 1B illustrate one aspect of a process wherein oil sand is mined then processed to form an oil sand slurry ready for hydrotransport (pumpable oil sand slurry). Oil sand mined from an oil sand deposit 2 by a power shovel 4 is fed into a hopper 6 of a preliminary conveyor 8. The preliminary conveyor 8 deposits a flow of the mined oil sand into a preliminary (or primary) crusher 10 that reduces the size of the mined oil sand to pieces of conveyable size (pre-crushed oil sand). From the preliminary crusher 10 the pre-crushed oil sand is fed to a transport conveyor 15, using a loading conveyor 12, where the particulate oil sand is transported along the transport conveyor 15 to a discharge end 17 of the transport conveyor 15. At the discharge end 17 of the transport conveyor 15, the pre-crushed oil sand is discharged through an intake opening 25 of a surge bin 20, to be discharged onto an apron feeder 30. From the apron feeder 30, the discharge oil sand is carried up a conveyor 40 and discharged into an intake opening 55 of the slurry preparation tower 50. The slurry preparation tower 50 takes the flow of particulate oil sand discharging from a discharge end 45 of the conveyor 40 and processes the flow of particulate oil sand to form a pumpable oil sand slurry.

The surge bin 20 is used to take what can be an irregular flow of oil sand being discharged from the transport conveyor 15 collect and meter this oil sand to provide a relatively constant feed rate of oil sand being carried up the conveyor 40 and into he slurry preparation tower 50.

While FIGS. 1A and 1B illustrates one system of processing oil sand, however, a person skilled in the art will appreciate that various other methods of processing oil sand could also be used.

FIG. 2 illustrates a surge bin 100 as known in the prior art. The surge bin 100 has a number of walls 110 that define an inner cavity where particulate material can collect. The surge bin 100 can also have an opening 112 and a discharge outlet 114. Particulate material such as oil sand can be fed into the surge bin 100 through the opening 112 where it will be discharged out the discharge outlet 114 and onto a conveyor 150 such as an apron feeder. A skirt 120 can be provided on the bottom end of the surge bin 100 surrounding the discharge outlet 114.

The feed rate of oil sand from the surge bin 100 can be altered by changing the speed of the conveyor 150 as it moves the oil sand in the first direction A. Increasing the speed of the conveyor 150 can increase the flow rate of the oil sand being discharged from the surge bin 100, while decreasing the speed of the conveyor 150 can decrease the flow rate of the oil sand being discharged from the surge bin 100.

In surge bins, such as surge bin 100 shown in FIG. 2, when lower to average grades of oil sand (i.e., around 9-10 wt % bitumen) are being passed through the surge bin 100, the flow rate of the oil sand being discharged from the surge bin is often directly proportional to the speed of the conveyor 150. However, for high grade oil sand (i.e. relatively high bitumen content of greater than 10 wt %), a flow rate limit can be reached where further increases in the speed of operation of the conveyor 150 does not result in significant additional flow rates of this high quality oil sand from the surge bin 100.

FIG. 3 illustrates a surge bin 200 modified for use with high grade oil sand. Surge bin 200 has a number of walls 210 that define an inner cavity. The surge bin 200 can have an opening 212 provided at a top end of the surge bin 200 and a discharge outlet 214. Particulate material such as oil sand can be fed into the surge bin 200 through the opening 212 to be subsequently discharged through the discharge outlet 214.

A conveyor 250, such as an apron feeder, can be provided beneath the discharge outlet 214 of the surge bin 200 so that particulate material discharged from the surge bin 200 through the discharge outlet 214 can be discharged onto the conveyor 250. The conveyor 250 can be driven to move particulate material that has been discharged out of discharge outlet 214 of the surge bin 200 and onto the conveyor 250 in a first direction B.

In one aspect, a skirt 220 can be provided surrounding the discharge outlet 214 and sized to run between the discharge outlet 214 and the conveyor 250. The skirt 220 can be used to control the amount of particulate material being discharged out of the discharge outlet 214. In one aspect, this skirt 220 can be formed of a heavy rubber or other flexible material.

The surge bin 200 can have a front wall 205 having a sloped portion 207. The front wall 205 can be positioned in the surge bin 200 so that particulate material that has been discharged onto the conveyor 250 is moved by the conveyor in the first direction B and underneath the front wall 205. In one aspect, the front wall 205 can be positioned to run substantially perpendicular across the conveyor 250 so that all of the particulate material being moved by the conveyor 250 must pass under the front wall 205 of the surge bin 200.

The sloped portion 207 of the front wall 205 can be sloped outwards so that the cross-sectional area of the discharge outlet 214 is greater than the cross-sectional area of the opening 212. In one aspect, the sloped portion 207 of the front wall 205 can begin down from the top of the front wall 205 so that an upper portion 209 of the front wall 205 is oriented substantially vertically. The sloped portion 207 can then slope outwards from the upper portion 209 to a bottom end of the front wall 205.

In one aspect, this sloped portion 207 can be angled at approximately forty-five (45) degrees.

Example 1

Experimentation has shown that surge bin 200 with the slanted front wall 205 can allow the flow rate of high grade oil sand to be increased beyond the upper limit that is experienced with a flat walled surge bin, such as surge bin 100 shown in FIG. 2. FIG. 4 is a graph of particulate material flow rates using each model of surge bin as a function of the conveyor (apron feeder) speed. Cold-flow modeling was performed do 1:8 scale models to obtain the results shown in FIG. 4. A first model was made in accordance with surge bin 100 shown in FIG. 2 and a second model was made in accordance with surge bin 200 shown in FIG. 3.

The solid black line with black solid squares shows the results obtained using the model made in accordance with the surge bin 100 shown in FIG. 2 (Prior Art). As can be seen from these results, when high grade oil sand was used with the first model, the flow rate reached an upper limit of around 2.5 kg/s and further increases in the conveyor speed (apron feeder speed) did not result in further significant increases beyond this limit. However, where masonry sand was used (masonry sand is used because it flows like a conventional granular material), an increase in conveyor speed resulted in a substantially linear increase in the average mass flow rate (see solid black line with black solid circles). Thus, it is clear that conventional prior art surge bins are not optimal when high grade oil sand is the feed.

A second test was performed with high grade oil sand and masonry sand using both models. As previously experienced, when using the first prior art model (the surge bin 100 shown in FIG. 2) with high grade oil sand, an increase in conveyor speed did not result in an increase in average mass flow rate of the oil sand (see dashed lines with the empty squares). Once again, when using masonry sand with the first prior art model, an increase in conveyor speed once again resulted in a corresponding increase in average mass flow rate of the masonry sand (see dashed lines with empty circles).

However, when using the second model in accordance with the surge bin 200 shown in FIG. 3 with high grade oil sand, the average mass flow rate of the high grade oil sand exceeded that shown using the first prior art model and the flow rate kept increasing as the speed of the conveyor was increased (see dashed line with crossed squares), resulting in an order of magnitude increase in flow rates at the highest conveyor speeds over using the first prior art model in accordance with the surge bin 100 shown in FIG. 2. While the flow of oil sand did not increase as much as with masonry sand (see the dashed lines with crossed circles), nevertheless, the flow of oil sand was significantly improved when using the angled wall surge bin as shown in FIG. 3.

Thus, from the graph shown in FIG. 4, it can be seen that there is a relatively insignificant difference between the performance of the model designed in accordance with surge bin 100 shown in FIG. 2 and the model designed in accordance with the surge bin 200 shown in FIG. 3 when using masonry sand. However, it is clear that the advantage of the present invention is achieved when using the surge bin having a sloped wall as shown in FIG. 3 for high grade oil sand as the feed material.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to those embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the full scope consistent with the claims, wherein reference to an element in the singular, such as by use of the article “a” or “an” is not intended to mean “one and only one” unless specifically so stated, but rather “one or more”. All structural and functional equivalents to the elements of the various embodiments described throughout the disclosure that are known or later come to be known to those of ordinary skill in the art are intended to be encompassed by the elements of the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. 

1. A surge bin having a top and a bottom comprising: a plurality of walls defining an inner chamber; and an opening at or near the top of the surge bin and a discharge outlet at or near the bottom of the surge bin, the discharge outlet positioned to discharge particulate material onto a conveyor; whereby at least one of the plurality of walls having a sloped portion sloping outwards towards the discharge outlet.
 2. The surge bin of claim 1 wherein the sloped portion is provided on a front wall.
 3. The surge bin of claim 2 wherein the front wall is positioned so that when the conveyor is operating, particulate material discharged onto the conveyor is moved by the conveyor towards and under the front wall.
 4. The surge bin of claim 1 wherein the sloped portion causes the discharge outlet to have a larger cross sectional area than the opening.
 5. The surge bin of claim 1 further comprising a skirt positioned between the discharge outlet and the conveyor.
 6. The surge bin of claim 1 wherein the sloped portion is angled outwards at approximately 45°.
 7. The surge bin of claim 2 wherein the front wall has an upper portion that is oriented substantially vertically and the sloped portion. 